How to Install GtkHash (Checksum Generator) in Ubuntu?

Checksum, as the name denotes, is a method that's developed to let users to check or compare, let's say a file that you're holding called "B" (assuming that it's a copy of an original file called "A") is corrupted or not while copying or moving. It's something a bit similar to the idea of a finger print, somewhat. 

How the heck can that happen?

To be honest guys, I'm not an expert on that subject. But to share my experience with you, there are (very few actually) occasions that after downloading a ISO (say an operating system) and then after burning it to a CD/DVD but while trying to boot into the OS, the CD/DVD rom says "corrupted disk" or something similar ("bugger!" errrr).

To make things worse, while burning CD/DVD in this case, the application wasn't able to detect any "corruptions" and as result now I have an entire CD/DVD wasted!. But if I used a checksum calculator before burning it into a CD or DVD then the app most probably be able to detect the "corruption".

GtkHash main window...

The reason I said "maybe" was because, sometimes these corruptions occur in a very very subtle ways thus it may not even be visible which only gives errors while trying to use it. But there are occasions however not only Checksum apps can let you identify corrupted files but they can even recover some of the damaged data too!.

Although not just while downloading these corruptions can occur while you're simply copying a file in between your local HDD or USB, etc.

I think the reason for such behavior is due to the fact that when copying or downloading, etc the OS first sends the data to the cached location on RAM and then to the HDD... thus in the process some of the data can be corrupted due to small voltage fluctuations on RAM, due to data collisions, or common data losses while downloading etc (scary stuff huh ;-) ). Whatever the reasons are, they can happen.

In thas sense, GtkHash is actually does not let you check for the integrity but it's a handy application that lets you calculate or create a Checksum for any given file and save it, thus say the data on that file is very very sensitive (perhaps it contains passwords or bank account numbers, etc).

Then after you moved/copied the file into a disk or any location that you want then you can later use a Checksum (also known as integrity check) checker to make sure whether it's corrupted or not.

Because for a password or especially for archives and encrypted data, even the most subtlest "data corruption" can make it un-usable!. CD/DVD burning applications usually come with a built in ability to check the integrity via Checksums generated by apps such as GtkHash.

It supports creating Checksums using various algorithms...

In that sense, GtkHash is a GTK written (obviously :D) Checksum generator that you can use to create a Checksum file for any given file under GNU/Linux using various algorithms.

You can install GtkHash in Ubuntu 11.04 Natty Narwhal, 10.10 and 10.04 by using the below command in the Command-line window.

sudo apt-get install gtkhash

It has a separate "list view" that lets managing multiple files with ease ...

That should do it. Use it wisely :P. Enjoy!.

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Install Nanny in Ubuntu - A Parent Control System for GNU/Linux!

Day by day, child safety and computers are a major concern for parents. The issue is that as the technology advances... the "opportunities" for someone to take advantage of your child is also rising. The best example is the social media sites.

The matters are complicated thus the party with the highest interests + power will always win, no matter how risky it can be. The best example is the proposal which took place few years ago to give Internet porn sites an extension of their own (I think it was ".xxx").

This was great news for parents especially because all we have to do to keep your kid using these types of websites was to install a simple firewall and tell it to block any site with the ".xxx" extension and all of those sites will be blocked using a single command. But the sad truth is that, it didn't happen!. To this day I have no idea of their reasons, yet this is the nature of the that world we live in.

To make things more worse, in MS Windows platform, there are actually several excellent parent control applications that once configured... well they are quite powerful. But in GNU/Linux, they're still somewhat, rare to find.

So, if you have installed Ubuntu (you can use it on other GNU/Linux distributions as well) and exhausted after trying to find a "decent" utility for that purpose, then there is such an app that has a simple GUI (GTK+written) and lets you do things such as ...

*. Control the time that your young ones spend their time using the PC.

*. Block the Web browser completely or add sites of your own that has to be blocked, etc.

The best "Nanny" ever!... ;-)

*. Enable/disable e-mail client usages.

*. Control instant messaging client using times or completely disabling it.

These are the options that you're given. Although when comparing with other apps, this may not sound like much, but I think when it comes to protecting your child from his/her Computer and internet that has GNU/Linux installed ... this application called "Nanny!" is pretty useful.

If you use Ubuntu 11.04 Natty Narwhal (should work in 10.04 and 10.10), you can install Nanny by entering the below command in your Terminal.

sudo apt-get install nanny

Few tips...

For instance, lets say under the "PC use time" tab, I entered 1 hour. Then this is a total value, meaning that the little ones can take breaks in between, only the total time they spent using the computer will be counted (as long as they're logged in to their accounts).

But lets say that, you wanted block them using the computer from 9 am to 10 am Monday. Then you can click on those "Green" buttons (on the appropriate application - web browser, pc usage, e-mail, etc)  which will turn them into Red, meaning that, at that time period, no matter how much time they've "left" to use the computer, still within that time-scale, it's completely forbidden!. You can cancel it by again clicking on the Red buttons as well.

The "1" hour I put does not "count" from 9am to 10am in Mondays...

If you want to block certain website access, then, as you can see from the below screenshot, after clicking on the "Web browser" tab, add the time period and then click on the "Configure" button which will let you add/block certain types of web sites.

The Nanny parent control system for GNU/Linux comes with an excellent help file which you can access by clicking on the "Help" button on the lower left end which explains pretty much everything. Good luck.

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Install Gufw in Ubuntu 11.04 Natty Narwhal!

GNU/Linux is well known for being highly stable and highly secure. Although different GNU/Linux distributions use different approaches when achieving a highly secured environment. For instance, Fedora Core comes with a firewall called iptables and does let you change reasonable amounts using a GUI of their own.

Ubuntu also uses the iptables but has a front-end for controlling it called, ufw (uncomplicated firewall). It's quite powerful but the only problem with ufw is... if you want to configure it for better security, then you'll have to use nothing but the ugly Terminal :P.

Gufw is written to "fill" that gap. Although, maybe because it's still kinda new and all... it won't give you an impressive amount of options ... but as a usual PC user all you want is to configure standard firewall related configurations, then Gufw is pretty useful nonetheless.

From configuring things like P2P (file sharing) protocols, configure individual applications based settings, edit services based settings/permissions, etc... Gufw does make it easier without a doubt.

P2P firewall settings....

If you use Ubuntu 11.04 Natty, then you can install Gufw by simply downloading the .deb package from here and double click on it once the download is complete. Then follow the instructions on your screen. That's it!.

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